Copper containing proteins play important roles in living systems because they are involved in the catalysis of a variety of oxidative metabolic processes. The thrust of the studies proposed herein is to further characterize structural and functional aspects of the crucial copper binding sites in these systems. Many of the proteins involved are quite complex and no single measurement will serve to define them. Accordingly, a multifaceted approach to these systems is proposed. Kinetic studies of metal uptake involving the apo-protein of the low molecular weight system azurin as well as those of the more complex laccase systems are proposed with the goal of developing the background that is needed to design the synthesis of mixed metal hybrid derivatives of the latter enzymes which will then be useful in follow-up mechanistic studies. In addition transient and steady-state kinetics studies as well as binding studies of the laccase enzymes are proposed and are aimed at delineating further information about the type 3 binding site and the mechanistic features of these oxidases. Studies of carefully designed small molecule systems are also proposed. One involves mixed donor polydendate ligand systems and is concerned with the preparation of a synthetic analogue of the blue copper site. Another involves H-nmr studies of electron transfer reactions and is concerned with assessing the applicability of the Marcus theory to understanding outersphere electron transfer reactions of copper centers with well defined coordination environments.